1. Field of the Invention
The present invention generally relates to a label printer for printing and issuing labels of a kind bearing thereon data such as a product name, price, xe2x80x9cBest Beforexe2x80x9d date (a recommended relishable date) and/or any other data associated with the product on which the label is affixed.
2. Description of the Prior Art
Label printers for printing and issuing labels are currently largely employed in a variety of industries. In general, the label printers are of a design wherein a ribbon of label carrier sheet carrying a row of blank labels adhering peelably to the label carrier sheet is utilized and the blank labels are successively printed and issued with data printed thereon. The data to be printed on each blank label include, for example, product name, price, xe2x80x9cBest Beforexe2x80x9d date (a recommended relishable date) and/or any other data associated with the product on which the eventually printed label is affixed.
By way of example, the Japanese Utility Model Publication No. 2-9983 discloses the label printer including a label supply unit accommodating therein a roll of ribbon-shaped label carrier sheet comprising a ribbon of backing sheet and a row of closely adjoining blank labels each adhering at an adhesive side thereof to the backing sheet, and a printer unit including a platen roll and a printer head. The ribbon-shaped label carrier sheet is successively drawn out from the label supply unit towards a printing station at which as the ribbon-shaped label carrier sheet is intermittently supplied through a nip region between the platen roll and the printer head, required or desired items of data are printed by the printer head on each label.
The prior art label printer of the type discussed above makes use of a roll holder for rotatably supporting the roll of the ribbon-shaped label carrier sheet. More specifically, as shown in FIG. 17, the roll holder employed in the prior art label printer comprises a support bar B having one end rigidly secured to a vertical wall lying parallel to the direction of transport of the ribbon-shaped label carrier sheet, and a retainer member C mounted detachably on the support bar B for retaining the label roll D of the ribbon-shaped label carrier sheet in position between the vertical wall A and the retainer member C. The retainer member C used therein is of a configuration including a boss C1 and a flange C2 of a diameter larger than the diameter of the support bar B.
While the label roll D is rotatably supported on the support bar B, the retainer member C is mounted on the support bar B with an end face C2xe2x80x2 of the flange C2 held in sliding contact with the adjacent end of the label roll D to thereby avoid a lateral displacement of the label roll D along the support bar B and, hence, to prevent the label roll D from being laterally separating out of the support bar B when the ribbon-shaped label carrier sheet is drawn out from the label roll D. To avoid any possible displacement of the retainer member C in a direction axially of the support bar B, the retainer member C can be fixed in position by fastening a stopper screw E once the retainer member C is set in position on one side of the label roll D.
A similar roll holder, but having a different structure such as shown in FIG. 18, is also largely utilized. As shown in FIG. 18, the roll holder includes a support bar F having a free end face, and a generally C-shaped, thin retainer member G having one end connected to the free end face of the support bar F for pivotal movement between folded and operative positions. When the label roll H is to be mounted on the support bar F, the retainer member G is held in the folded position in which the retainer member G is encompassed within the perimeter of the free end face of the support bar F as shown to allow passage of the label roll H over and onto the support bar F. Once the label roll H has been mounted on the support bar F, the retainer member G is pivoted to the operative position, shown by the phantom line, to overlap with the adjacent end face of the roll H to thereby prevent the label roll H from being displaced axially of the support bar F.
According to the previously mentioned publication discussed with reference to FIG. 17, the retainer member C makes use of the stopper screw E which, when fastened, allows the retainer member C to be fly positioned at the very location at which the stopper screw E is fastened. Accordingly, by repositioning the retainer member C on the support bar B and then fastening the stopper screw E, the roll holder is capable of accommodating label rolls of different axial lengths, that is, label carrier ribbons of different widths, one at a time.
However, when the label roll D is desired to be replaced with a different label roll of the same or different axial length, the roll holder of the structure shown in FIG. 17 requires a series of jobs of undoing the stopper screw E with the use of a screw driver or the like to allow the retainer member C to be removed from the support bar B, re-mounting the retainer member C onto the support bar B after the label roll D has been replaced with the different label roll, and fastening the stopper screw E again with the use of the screw driver. This is cumbersome and time-consuming and, therefore, replacement of the label rolls is indeed inefficient.
On the other hand, with the roll holder of the structure shown in FIG. 18, replacement of the label roll H with the different label roll can be efficiently carried out since removal of the label roll H and mounting of the different label roll can be accomplished by merely pivoting the retainer member G between the folded and operative positions. However, fitting of the retainer member G to the free end face of the support bar F involves the following problems.
More specifically, the retainer member G secured to the free end face of the support bar F is incapable of being moved in a direction axially of the support bar F. Accordingly, the retainer member G cannot be repositioned according to the axial length of the label roll H and, hence, the roll holder of FIG. 18 is incapable of accommodating the label carrier ribbons of different widths one at a time.
Also, since the folded position for the retainer member G must be such that the retainer member G is encompassed within the perimeter of the free end face of the support bar F to allow the label roll H to be mounted onto the support bar F without being obstructed by the retainer member G, the radial distance shown by h in FIG. 18, measured between the point of pivot of the retainer member G and a free end of the retainer member G remote from the point of pivot when the retainer member G is pivoted to the operative position, is limited. This means that when the label roll of a relatively large diameter, that is, having a radius greater than the radial distance h is mounted on the support bar F, an outer peripheral portion of the label roll H will protrude radially outwardly from the retainer member G in the operative position and, therefore, the retainer member G will be incapable of retaining the label roll H in the right shape. More specifically, if some of outer turns of the label roll H are loosened while the label carrier ribbon is drawn out from the label roll H, the retainer member G is unable to retain such some of the outer turns of the label roll H substantially in flush with the opposite end face of the remaining label roll H and will, therefore, be separated from the remaining turns of the label roll H.
Accordingly, the present invention has been devised with a view to substantially eliminating the above discussed problems inherent in the prior art label printers and is intended to provide an improved label printer wherein not only can the label roll of a varying diameter can be assuredly kept in position on a support bar, but also the label roll of any different diameter can be mounted on the support bar easily and quickly.
To this end, the present invention provides a label printer for printing predetermined data on and issuing labels, which printer includes a roll supply unit adapted to accommodate a roll of ribbon-shaped label sheet; a vertical wall disposed along and perpendicular to a predetermined path of travel of a ribbon of label sheet drawn outwardly from the roll in the roll supply unit; a tubular roll support shaft having a hollow defined therein and connected to the vertical wall so as to extend perpendicular thereto, said roll support shaft having a slot defined therein in communication with the hollow thereof; a slide member movably accommodated within the hollow of the roll support shaft for movement in a direction axially of the roll support shaft; and a lever member connected to the slide member for pivotal movement about a point of pivot between folded and erected positions relative to the roll support shaft.
The lever member when in the erected position has one end portion protruding outwardly from the hollow of the roll support shaft through the slot, to thereby retain the roll of the ribbon-shaped label sheet in position on the roll support shaft to avoid any possible lateral displacement thereof. On the other hand, the lever member when in the folded position lies substantially parallel to a longitudinal axis of the roll support shaft to allow the roll of the ribbon-shaped label sheet to be mounted onto the roll support shaft.
Preferably, the lever member has the opposite end portion extending away from the point of pivot in a direction counter to said one end portion thereof so that when the lever member is pivoted to the erected position, such opposite end portion of the lever member can be brought into press-contact or engagement with an inner wall surface of the roll support shaft to thereby lock the lever member at the erected position.
Also preferably, the slide member has a thickened wall portion engageable with a side face of an opposite end portion of the lever member when the lever member is pivoted to the erected position, so that said thickened wall portion when brought into engagement with the side face of the opposite end portion of the lever member can expand the slide member to bring an outer wall face of the slide member into contact with an inner wall surface of the roll support shaft to thereby lock the lever member at the erected position.
Yet preferably, the slide member has side walls opposite to each other and has a slit defined in each of the side walls so as to extend away from the vertical wall, so that the slit in each of the side walls can divide the corresponding side wall into two wall segments, at least one of said wall segments having a resiliency. In this arrangement, the at least one of the wall segments is formed with a projection for urging an inner wall surface of the roll support shaft and, accordingly, when the slide member slides within the hollow of the roll support shaft, a slide resistance of a predetermined magnitude is developed between the projection and the inner wall surface of the roll support shaft.
In a preferred embodiment of the present invention, the lever member has an index marking alignable with one end face of the roll of the ribbon-shaped label sheet when the roll is mounted on the roll support shaft, to thereby indicates a position of the lever member at which the lever member is pivoted to the erected position to retain the roll in position on the roll support shaft.
In another preferred embodiment of the present invention, the lever member and the slide member are integrally assembled into a single lever unit whereby the lever member and the slide member can be mounted inside the roll support shaft by inserting the lever unit axially into the hollow of the roll support shaft.
Furthermore, in a further preferred embodiment of the present invention, the slide member includes a third wall disposed between opposite side walls thereof, said third wall having two parallel slits defined therein so as to extend in a direction inwardly thereof and away from the vertical wall so as to define an isolated portion discontinued from the opposite side walls thereof and having a resiliency. In this design, the isolated portion having an outer surface formed with an engagement protruding outwardly therefrom is engageable with one end of the slot in the roll support shaft adjacent the vertical wall after the single lever unit is mounted into the hollow of the roll support shaft, to thereby retain the single lever unit therein while being prevented from detachment out of the hollow by means of the engagement engaged with the end of the slot in the roll support shaft adjacent the vertical wall.
According to the label printer embodying the present invention, merely by erecting the lever member relative to the roll support shaft, an undesirable lateral displacement of the label roll along the roll support shaft can advantageously and conveniently suppressed.
Accordingly, when the label roll is to be mounted onto the roll support shaft, no job of undoing and fastening the screw member such as required in the prior art label printer is required in the present invention and, merely by erecting the lever member in the manner described above, the label roll can easily and quickly mounted onto the roll support shaft. Therefore, the efficiency with which the label roll is mounted can be increased advantageously.
Also, since the slide member is so designed as to be slidable within the hollow of the roll support shaft, the position at which the lever member is to be erected can be adjusted according to the axial length of the label roll, that is, the width of the label carrier sheet forming the label roll.
Again, since when the lever member is folded, i.e., brought to the folded position, the lever member extends substantially parallel to the longitudinal axis of the roll support shaft, mounting of the label roll onto the roll support shaft will not be obstructed by the lever member even though that end portion of the lever member that protrudes outwardly from the roll support shaft through the slot has a substantial length. Accordingly, that end portion of the lever member can have an increased length so that the lever member when in the erected position protrudes a correspondingly increased distance outwardly from the roll support shaft and can therefore accommodate an increased radius of the label roll while retaining the label roll of the relatively great radius in position on the roll support shaft without allowing outer turns of the label rolls being loosened. Also, even when the ribbon of the label carrier sheet being drawn out from the label roll floats, some of the outer turns of the label roll will not be loosened.
According to the label printer in which when the lever member is erected relative to the roll support shaft the opposite end portion of the lever member can be brought into engagement with the inner wall surface of the roll support shaft, the lever member can assuredly be locked at the erected position and, therefore, there is no possibility that as the lever member is being erected the lever member may undergo an arbitrary movement about the point of pivot accompanied by displacement of the position at which the lever member is to be erected to retain the label roll on the roll support shaft.
Also, the thickened wall portion engageable with a side face of an opposite end portion of the lever member when the lever member is pivoted to the erected position is formed in the slide member so that the thickened wall portion when brought into engagement with the side face of the opposite end portion of the lever member can expand the slide member to bring an outer wall face of the slide member into contact with an inner wall surface of the roll support shaft to thereby lock the lever member at the erected position. Accordingly, the possibility that as the lever member is being erected the lever member may undergo an arbitrary movement about the point of pivot accompanied by displacement of the position at which the lever member is to be erected to retain the label roll on the roll support shaft can be equally eliminated advantageously.
In the design in which when the lever member is erected the end portion of the lever member extended with respect to the point of pivot is brought into engagement with the inner wall surface of the roll support shaft, erection of the lever member takes place in such a manner that a relatively large force acts on the lever member being pivoted towards the erected position immediately following the point at which that end portion of the lever member is just brought into engagement with the inner wall surface of the roll support shaft. At this time, it may occur that the slide member will move within the hollow of the roll support shaft. However, the employment of the above described design is effective to prevent the slide member from being arbitrarily moved within the hollow of the roll support shaft at the time of erection or folding of the lever member.
Where the projection is formed in the slide member for urging the inner wall surface of the roll support shaft so that the slide resistance of a predetermined magnitude can be developed between the projection and the inner wall surface of the roll support shaft during the sliding motion of the slide member within the hollow of the roll support shaft, the possibility can be eliminated in which an arbitrary movement of the slide member within the hollow of the roll support shaft may result in change in position at which the lever member is to be erected to retain the label roll in position on the roll support shaft. Accordingly, in the event of replacement of one label roll with another label roll having the same axial length as that of such one label roll, no repositioning of the slide member is required after such another label roll is mounted onto the roll support shaft by folding the lever member, and erection of the lever member is sufficient to retain such another label roll in position on the roll support shaft without repositioning the slide member within the hollow of the roll support shaft.
Furthermore, the provision in the lever member of the index marking alignable with one end face of the roll of the ribbon-shaped label sheet when the roll is mounted on the roll support shaft, to thereby indicates a position of the lever member at which the lever member is pivoted to the erected position to retain the roll in position on the roll support shaft, is effective and advantageous in that erection of the lever member after the position indicated by the index marking when the lever member is folded has been aligned with one end face of the label roll can result in the lever member being erected at the exact position at which the label roll is to be retained.
Where, for example, when the lever member is pivoted to the erected position relative to the roll support shaft, the opposite end portion of the lever member is brought into engagement with the inner wall surface of the roll support shaft, a reactive force may be transmitted from the roll support shaft to the lever member to move the slide member within the hollow of the roll support shaft. Once this occurs, the position at which the lever member is to be erected is displaced from the exact position at which the label roll is to be retained, even though the attendant worker has erected the lever member towards the erected position after having aligned with the exact position, and, accordingly, the necessity will occur that the lever member has to be manipulated frequently to pivot it between the erected and folded positions so that the lever member can be erected at the exact position for retaining the label roll. However, the provision of the index marking in the manner described above is effective and advantageous in that the position at which the lever member has to be erected can easily be grasped at a single sight, resulting in increase of the workability.
Where the design is employed in the label printer in which the lever member and the slide member are integrally assembled into a single lever unit so that the lever member and the slide member can be mounted inside the roll support shaft merely by inserting the lever unit axially into the hollow of the roll support shaft, mounting of the lever member and the slide member into the hollow of the roll support shaft can be facilitated. Also, while the slot is defined in the roll support shaft within which the lever member can pivot between the folded and erected position, the single lever unit can be inserted into the hollow of the roll support shaft from one end thereof adjacent the vertical wall and, therefore, the end of the roll support shaft opposite to such one end can be formed integrally with side walls except for a portion thereof forming a part of the path of pivotal movement of the lever member, thereby securing a sufficient rigidity of the roll support shaft.
According to the present invention, when the single lever unit is inserted into the hollow of the roll support shaft, the projection integral with the slide member is brought into engagement with one end of the slot in the roll support shaft to thereby avoid any possible axial detachment of the slide member from the roll support shaft. This design is effective in that when the single lever unit is to be inserted into the hollow of the roll support shaft, the attendant worker can feel a positive sound of reaction from the lever unit, indicating that the single lever unit has been assuredly mounted inside the hollow of the roll support shaft.